CN108573074A - A kind of computational methods of car clutch pedal force characteristic - Google Patents

Abstract

The invention discloses a method for calculating the pedal force characteristics of an automobile clutch, which comprises the following steps: step 1, obtaining the main parameters of each component of the clutch hydraulic operating system; The principle establishes the pedal mechanism model, the hydraulic system model, and the clutch assembly model; step 3, install force and displacement sensors, and obtain input data; step 4, carry out kinematics and mechanical analysis on each part of the model, and finally obtain the pedal force characteristic curve. The invention can effectively guide the actual structure design, greatly reduce the working time and cost of the actual design, and ensure the reliability of the design.

Description

A Calculation Method of Automobile Clutch Pedal Force Characteristics

technical field

The invention relates to a calculation method for the characteristics of the automobile clutch and its control system, in particular to a calculation method for the characteristics of the pedal force of the automobile clutch.

Background technique

As a key component of automobile power transmission and interruption, the clutch plays multiple roles in the transmission system of the automobile, such as torque transmission, separation and coupling, vibration reduction protection and overload protection, and the performance of the clutch operating mechanism directly affects the comprehensive performance of the clutch. Pros and cons. The realization of functions such as starting the engine, changing gears, and preparing to stop the car is inseparable from the clutch control mechanism. If the operating force of the clutch operating mechanism is too large or too small, not only the driver will be easily fatigued, but also the clutch will not be shifted in place, causing the friction plate of the driven disc to be damaged, resulting in vehicle failure. With the rapid development of automobile technology and people's higher requirements for vehicle driving comfort, automobile manufacturers and users have higher and higher requirements for the performance of clutches and their control systems. For this reason, earth-shaking changes have taken place in the clutch control mechanism, and it has experienced a historic change from scratch, from manual to automatic. However, although there is an automatic clutch, the traditional manual clutch still has its irreplaceable value and significance. With its advantages such as mature technology, low price, good driving performance and convenient maintenance, it will be used for a long period of time in the future. It will still be used a lot for a while.

According to relevant survey data, in some auto maintenance companies, the maintenance rate of clutches often ranks among the top three among all accessories. The main faults are reflected in poor clutch separation, clutch slipping, and heavy pedals. Analysis of the reasons shows that, in addition to the material selection and structural design of the clutch itself, the clutch operating mechanism is also an important cause of the above faults, so it is necessary to conduct a comprehensive and in-depth study on the clutch operating mechanism. The clutch pedal force characteristic is the main manifestation of the performance of the clutch control system. Through the establishment of the clutch hydraulic control system model, the formula of the pedal force characteristic curve is deduced, which will provide theoretical guidance for the optimal design and troubleshooting of the clutch control system. Improve the reliability, stability and maintenance performance of the control mechanism, and lay a theoretical foundation for the further design and development of low-cost and high-efficiency clutch control system related components, which is also important for improving the characteristics of the clutch control system and the driving comfort of the driver reference significance.

Contents of the invention

The technical problem to be solved by the present invention is to provide a calculation method for the pedal force characteristics of the automobile clutch, which can derive the characteristic curve formulas of the pedal force and the pedal stroke of the clutch hydraulic control system under different structural parameters, and obtain the corresponding characteristic curve. The calculated characteristic curve can effectively guide the actual structure design, greatly reduce the actual design work time and cost, and ensure the reliability of the design.

In order to solve the problems of the technologies described above, the technical solution adopted in the present invention is:

A method for calculating the pedal force characteristics of an automobile clutch, wherein the clutch hydraulic control system components include: a clutch assembly, a release bearing, a hydraulic master cylinder and a working cylinder, an oil pipe, a pedal mechanism, and a booster spring, including the following steps:

Step 1, obtain the main parameters of each component of the clutch hydraulic control system, the main parameters include: the separation characteristic curve of the clutch assembly (the separation force and separation stroke of the hydraulic release bearing), hydraulic cylinder parameters, booster spring parameters, pedal mechanism key Point position coordinates, force and stroke transmission efficiency, fork lever ratio.

Step 2: Establish the clutch hydraulic control system model: including the pedal mechanism model, the hydraulic system model, and the clutch assembly model. According to the transmission route of the pedal force and stroke, it can be known that the pedal force and pedal stroke first act on the pedal mechanism, then pass through the hydraulic system, and finally Reach the clutch assembly, so the three parts of the pedal mechanism, hydraulic system and clutch can be modeled and analyzed according to its transmission route;

Step 3, install force and displacement sensors, and obtain input data: place the clutch hydraulic control system as a real vehicle, install force and displacement sensors at the release bearing of the clutch control system, and use the A/D acquisition card to collect the force at the clutch release bearing Sensor and displacement sensor data to obtain separation force and separation stroke;

Step 4: Integrate the relationship between the calculation results of each model to obtain the calculation results: Correspond the separation force and separation stroke data obtained in the step 3 test to the pressure and stroke of the working cylinder piston, and substitute them into the calculation to obtain the corresponding The relationship between pedal force and pedal stroke.

Further, in step 1, the hydraulic cylinder parameters include the installation angle of the master cylinder, the diameter of the master cylinder, the idle stroke of the master cylinder, and the diameter of the working cylinder;

Described assist spring parameter comprises free length, spring stiffness;

The key point position coordinates of the pedal mechanism include the rotation center point of the pedal arm, the stepping point on the pedal surface, the hinge point of the compression spring and the pedal arm, the fixed point of the compression spring and the pedal assembly, the hinge point of the master cylinder push rod and the pedal arm, the master cylinder Hinge point with master cylinder push rod.

Further, in step 2, the pedal mechanism model includes a pedal mechanism and a booster spring, which is regarded as a geometric plane mechanism, and a coordinate system is established with the pedal arm rotation center point as the coordinate origin, and motion analysis and mechanical analysis are performed on it, The relationship between the pedal force (stroke) and the piston thrust (stroke) of the master cylinder and the relationship between the pedal stroke and the booster spring equivalent to the pedal booster can be obtained when there is no booster effect.

Further, in step 2, the hydraulic system model mainly includes a master cylinder, a working cylinder and hydraulic oil pipes, using the principles of motion dynamics and fluid mechanics, kinematic analysis and force analysis are carried out to obtain the master cylinder piston thrust (stroke ) and the relationship between the piston thrust (stroke) of the working cylinder.

Further, in step 2, the clutch assembly model includes a driven plate, a pressure plate, and a flywheel, and the separation characteristic curve of the clutch assembly, that is, the relationship curve between the separation force and the separation stroke, is measured through an experimental test method.

Further, the release bearing of the automobile clutch hydraulic control system is a hydraulic or shift fork release bearing, and the booster spring is a compression spring or torsion spring.

Further, the diameter of the master cylinder and the diameter of the working cylinder in the hydraulic cylinder parameters are equivalent diameters, which are obtained by calculating the equivalent diameters.

Further, the force and stroke transmission efficiency include force transmission efficiency and stroke transmission efficiency respectively, and because there is energy loss and volume loss in the process of actually stepping on the pedal and releasing the pedal, the force transmission efficiency will be different in the process and return , the travel transfer efficiency is the same during the process and return.

Compared with the prior art, the present invention has the following positive effects:

1) The present invention is a theoretical formula derivation of the characteristics of the clutch hydraulic control system, which can be used to guide the design of the structural parameters of the clutch and its control system.

2) The present invention can calculate the pedal force characteristic curves of various clutch assemblies and their control systems, and has wide applicability.

3) The present invention can provide a theoretical basis and a reference basis for the test results of the clutch hydraulic control system test bench.

4) The present invention can compile it into a check design software for a corresponding clutch and its control system, which is used to check whether the parameter matching of the clutch and its control system is reasonable on a computer, and the calculation results can be obtained in advance. The structural size of the clutch and its control system can effectively guide the actual structural design, greatly reduce the actual design work time and cost, and ensure the reliability of the design.

Description of drawings

Fig. 1 is a simplified structural diagram of a clutch hydraulic control system according to an embodiment of the present invention.

Fig. 2 is a transmission route diagram of pedal force and travel in the embodiment of the present invention.

Fig. 3 is a schematic diagram of the pedal mechanism model and the position coordinates of the corresponding relationship points according to the embodiment of the present invention.

Fig. 4 is a schematic diagram of the force on the pedal mechanism of the embodiment of the present invention.

Fig. 5 is a schematic diagram of the force of the compression spring type booster spring according to the embodiment of the present invention.

Fig. 6 is a schematic diagram of a hydraulic system model of an embodiment of the present invention.

Fig. 7 is a schematic diagram of data acquisition of separation force and stroke according to the embodiment of the present invention.

Fig. 8 is a calculated pedal force characteristic curve of the embodiment of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention more clear, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

The invention relates to a calculation method for the pedal force characteristic of an automobile clutch. The method deduces the characteristic curve formula of the pedal force and the pedal stroke of the clutch hydraulic control system, and can obtain the corresponding characteristic curves under different structural parameters. The calculated characteristic The curve can effectively guide the actual structural design, greatly reducing the actual design work time and cost, and ensuring the reliability of the design. The simplified structure diagram of the clutch hydraulic control system is shown in Figure 1, which mainly includes: clutch assembly 1, release bearing 2, working cylinder 3, hydraulic oil pipe 4, master cylinder 5, pedal mechanism 6, compression spring booster spring 7 The driver pushes the master cylinder 5 pushrod by stepping on the clutch pedal in the pedal mechanism 6, so that the master cylinder piston pushes the oil in the hydraulic line 4 to the working cylinder 3, and then acts on the piston of the working cylinder 3, so that the working cylinder The push rod of 3 pushes the clutch release shift fork, and the release shift fork moves the release bearing 2, and the release bearing 2 promotes the separation of the clutch assembly 1, so that the clutch driven disc is separated from the engine flywheel, and the engine power transmission is cut off. Include the following steps:

Step 1, obtain the main parameters of each component of the clutch hydraulic control system, the main parameters of the components include: the separation characteristic curve of the clutch assembly (the separation force and separation stroke of the hydraulic release bearing), hydraulic cylinder parameters, power spring parameters, pedal mechanism Key point position coordinates, force and stroke transmission efficiency, fork lever ratio.

For the separation characteristic curve of the clutch assembly, it can be measured by installing force and displacement sensors; for the hydraulic cylinder parameters and booster pedal parameters, it can be searched with reference to the corresponding model; for the key point position coordinates of the pedal mechanism, It can be measured by three coordinates; the force and stroke transmission efficiency can be based on empirical values, the force transmission efficiency process is generally 75%, the return stroke is 70%, and the stroke transmission efficiency is generally 95%; for the shift fork Lever ratio, since the hydraulic release bearing is used, the lever ratio of the shift fork is 1.

Step 2. Establish the clutch hydraulic control system model: the transmission route of the pedal force and stroke can be obtained from the working principle of the clutch hydraulic control system. As shown in Figure 2, it can be known that the pedal force and pedal stroke first act on the pedal mechanism, and then pass through system, and finally to the clutch assembly. Therefore, the three parts of the pedal mechanism, hydraulic system and clutch can be modeled and analyzed according to the transmission route.

The pedal mechanism model and the corresponding key point position coordinates are shown in accompanying drawing 3 and table 1 respectively,

Table 1 Definition of each key position of the pedal mechanism

Taking the simplified mechanism of the pressure spring type power-assisted clutch pedal as an example, with the center of rotation of the pedal arm as the origin of the coordinates, a Cartesian coordinate system is established to analyze the motion of the pedal mechanism and calculate the coordinates P _i '(x _i , y _i ) (i=1, 2, 4, 5). And carry out mechanical analysis on it, as shown in Figure 4, the relationship between the pedal force and the piston thrust of the master cylinder can be obtained when there is no power assist:

Among them, F ₁ is the pedal force when there is no power assist, F _Z is the force of the master cylinder push rod point on the master cylinder piston, l ₀₁ is the distance from point P ₀ to point P ₁ , and l ₀₄ is the distance from point P ₀ to point P ₄ , β ₁ is the angle between the P ₄ 'P ₀ line and the P ₄ 'P ₅ ' line, β ₂ is the angle between the P ₄ 'P ₅ ' line and the F ₅ direction, and the coordinates of each point are known in the formula value, so sinβ ₁ and cosβ ₂ can be obtained by vector angle:

Carry out force analysis on the compression spring type booster spring, as shown in Figure 5, and obtain the relationship between the booster spring equivalent to the pedal booster and the pedal stroke:

Among them, F _zhu is the assist spring equivalent to the pedal assist, L _s is the original length of the spring, K _S is the stiffness, l ₀₂ is the distance from point P ₀ to point P ₂ , l ₂₃ 'point P ₂ to point P ₃ ' The distance, _sinθ3 , can be found by:

Note that θ ₁ ＝∠P ₃ P ₀ X＝arccos(x ₃ /l ₀₃ '), θ ₂ ＝∠P ₂ P ₀ X＝arccos(x ₂ /l ₀₂ '), θ ₃ ＝∠P ₀ P ₂ ' _P3 . From the law of sines we know:

The hydraulic system model, as shown in accompanying drawing 6, mainly includes a master cylinder, a working cylinder and a hydraulic oil pipe. Before mechanical analysis, the following assumptions are made to the system:

(1) Assume that there is no gap between the working cylinder push rod and the piston in the hydraulic system;

(2) Ignore the influence of system pressure loss and volume loss on system characteristics, and assume that the pressure in the system equilibrium state is zero;

(3) For the concentric clutch hydraulic control system, it is assumed that the stroke of the release bearing is the stroke of the piston of the working cylinder, and the separation force is the thrust of the push rod of the working cylinder;

(4) In the system, it is assumed that the push rod is a rigid body, and its mass is negligible, only the mass of the piston is considered.

It can be seen from Figure 6 that during the process of depressing the clutch pedal, the force analysis on the piston of the master cylinder shows that the main force is that the pedal force is equivalent to the force of the push rod of the master cylinder, the spring holding force, the liquid pressure, and The friction force between the piston and the inner and outer walls of the cylinder; similarly, the force analysis of the working cylinder shows that its main forces are hydraulic pressure, force of the release bearing, holding force of the return spring and friction resistance of the inner and outer walls of the cylinder. According to the above force analysis, the mechanical balance equations of the master cylinder and the working cylinder piston can be obtained as follows:

During this process, the push rod of the master cylinder pushes the piston to move, so that the hydraulic oil in the oil pipe is compressed, and the pressure in the pipe gradually increases and then decreases. , The moving speed of the piston of the working cylinder and the diameter of the cylinder are determined, as shown in the following formula:

In the formula, M _Z , M _g are the piston mass (Kg) of the main cylinder and working cylinder, c _Z , c _g are the piston movement damping of the main cylinder and working cylinder (N/(mm s), F _Z , F _g are mainly Cylinder, working cylinder piston thrust (N), x _z , x _g main cylinder, working cylinder piston displacement (mm), Q is flow change (mm ² /s), P is tubing pressure (Pa), β is volume Modulus (Pa), V is oil volume (mm ³ ).

In the process of releasing the pedal, similarly use the principles of motion dynamics and fluid mechanics to analyze its force, and the relationship between the piston thrust (stroke) of the master cylinder and the piston thrust (stroke) of the working cylinder can be obtained;

The clutch assembly model includes a driven plate, a pressure plate, a flywheel, etc., and the separation characteristic curve of the clutch assembly, that is, the relationship curve between the separation force and the separation stroke, can be measured by an experimental test method.

Step 3, install force and displacement sensors, and obtain input data: Figure 7 shows the schematic diagram of data acquisition of separation force and separation stroke. Place the clutch hydraulic control system in the same way as a real vehicle, and install it at the release bearing of the clutch control system. The force and displacement sensor uses the A/D acquisition card to collect the force sensor and displacement sensor data at the clutch release bearing to obtain the separation force and separation stroke.

Step 4: Integrate the calculation results of each model to obtain the calculation results: The separation force and separation stroke data obtained in the test in Step 3 correspond to the pressure and stroke of the working cylinder piston, which can be substituted into the calculation to obtain the corresponding pedal force and stroke. The relational expression of the pedal stroke:

In the formula, F is the pedal force when the power assist is considered, F _Z is the thrust of the main cylinder piston push rod (obtained from step 2), and F _zhu is the equivalent to the pedal power of the booster spring (obtained from step 2).

Accompanying drawing 8 has provided the pedal force characteristic graph that the present invention calculates, abscissa is pedal stroke, and ordinate is pedal force, has provided the relational graph of pedal force and pedal stroke when assisting and without assisting among the figure .

The above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, rather than limiting the implementation of the present invention. For those of ordinary skill in the art, other changes or changes in different forms can be made on the basis of the above description. It is not necessary and impossible to exhaustively list all the implementation manners here. All modifications, equivalent replacements and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the claims of the present invention.

Claims (8)

1. A calculation method of automobile clutch pedal force characteristics, said clutch hydraulic control system parts include: clutch assembly, release bearing, master cylinder and working cylinder, oil pipe, pedal mechanism, booster spring, it is characterized in that: comprise the following steps : Step 1, obtain the main parameters of each component of the clutch hydraulic control system, the main parameters include: the separation characteristic curve of the clutch assembly, the parameters of the hydraulic cylinder, the parameters of the booster spring, the position coordinates of the key points of the pedal mechanism, the transmission efficiency of force and stroke, Fork lever ratio; Step 2, establish the clutch hydraulic control system model: including pedal mechanism model, hydraulic system model, clutch assembly model; Step 3, install force and displacement sensors, and obtain input data: place the clutch hydraulic control system as a real vehicle, install force and displacement sensors at the release bearing of the clutch control system, and use the A/D acquisition card to collect the force at the clutch release bearing Sensor and displacement sensor data to obtain separation force and separation stroke; Step 4: Integrate the relationship between the calculation results of each model to obtain the calculation results: Correspond the separation force and separation stroke data obtained in the step 3 test to the pressure and stroke of the working cylinder piston, and substitute them into the calculation to obtain the corresponding The relationship between pedal force and pedal stroke. 2. the computing method of automobile clutch pedal force characteristic as claimed in claim 1 is characterized in that: in step one, The hydraulic cylinder parameters include the installation angle of the main cylinder, the diameter of the main cylinder, the idle stroke of the main cylinder, and the diameter of the working cylinder; Described assist spring parameter comprises free length, spring stiffness; The position coordinates of the key points of the pedal mechanism include the coordinates of the center of rotation of the pedal arm, the coordinates of the stepping point on the pedal surface, the coordinates of the hinge point of the compression spring and the pedal arm, the coordinates of the fixed point of the compression spring and the pedal assembly, the coordinates of the master cylinder push rod and The coordinates of the hinge point of the pedal arm, the coordinates of the hinge point of the master cylinder and the push rod of the master cylinder. 3. the computing method of automobile clutch pedal force characteristic as claimed in claim 1 is characterized in that: in step 2, described pedal mechanism model comprises pedal mechanism and booster spring, is regarded as geometric plane mechanism, it is rotated with pedal arm The center point is the coordinate origin to establish a coordinate system, and the motion analysis and mechanical analysis can be carried out to obtain the relationship between the pedal force and the piston thrust of the master cylinder and the relationship between the pedal stroke and the booster spring equivalent to the pedal booster when there is no booster effect. 4. the computing method of automobile clutch pedal force characteristic as claimed in claim 1, is characterized in that: in step 2, described hydraulic system model mainly comprises master cylinder, working cylinder and hydraulic oil pipe, by using motion dynamics and fluid mechanics According to the principle, the kinematic analysis and force analysis are carried out to obtain the relationship between the piston thrust of the master cylinder and the piston thrust of the working cylinder. 5. The computing method of automobile clutch pedal force characteristic as claimed in claim 1, is characterized in that: in step 2, described clutch assembly model comprises driven plate, pressure plate, flywheel, records clutch assembly by test method. The resulting separation characteristic curve, that is, the relationship curve between the separation force and the separation stroke. 6. The calculation method of the pedal force characteristic of automobile clutch as claimed in claim 1, characterized in that: the release bearing of the hydraulic control system of the automobile clutch is a hydraulic type or a shift fork type release bearing, and the booster spring is a compression spring or torsion Reed assist spring. 7. The computing method of automobile clutch pedal force characteristic as claimed in claim 1, is characterized in that: master cylinder diameter and working cylinder diameter in described hydraulic cylinder parameter are equivalent diameters, obtain by the computing method of equivalent diameters. 8. The calculation method of automobile clutch pedal force characteristic as claimed in claim 1, it is characterized in that: described force and stroke transmission efficiency comprise force transmission efficiency and stroke transmission efficiency respectively, and due to the process of actually stepping on the pedal and releasing the pedal There is energy loss and volume loss, so the force transmission efficiency will be different during the process and return, and the stroke transmission efficiency is the same during the process and return.